<template>
  <div>
    <el-select
      :value="valueTitle"
      :disabled="disabled"
      :clearable="clearable"
      @clear="clearHandle"
      :filterable="filterable"
      :filter-method="filterMethod"
      @visible-change="onChange"
      ref="select"
    >
      <!-- <el-input
        placeholder="输入关键字进行过滤"
        v-model="filterText"
        v-if="filterable"
      ></el-input> -->
      <el-option :value="valueTitle" :label="valueTitle" ref="options">
        <el-tree
          id="tree-option"
          ref="selectTree"
          :accordion="accordion"
          :data="options"
          :props="props"
          :node-key="props.value"
          :default-expanded-keys="defaultExpandedKey"
          @node-click="handleNodeClick"
          :expand-on-click-node="false"
          :filter-node-method="filterNode"
        ></el-tree>
      </el-option>
    </el-select>
  </div>
</template>
<script>
export default {
  name: 'ebs-tree-select',
  props: {
    /* 配置项 */
    props: {
      type: Object,
      default: () => {
        return {
          value: 'id', // ID字段名
          label: 'title', // 显示名称
          children: 'children' // 子级字段名
        };
      }
    },
    /* 选项列表数据(树形结构的对象数组) */
    options: {
      type: Array,
      default: () => {
        return [];
      }
    },
    /* 初始值 */
    value: {
      type: String,
      default: () => {
        return null;
      }
    },
    /* 可清空选项 */
    clearable: {
      type: Boolean,
      default: () => {
        return true;
      }
    },
    /* 自动收起 */
    accordion: {
      type: Boolean,
      default: () => {
        return false;
      }
    },
    disabled: {
      type: Boolean,
      default: () => {
        return false;
      }
    },
    filterable: {
      type: Boolean,
      default: () => {
        return false;
      }
    }
  },
  data() {
    return {
      valueId: this.value, // 初始值
      valueTitle: '',
      defaultExpandedKey: [],
      filterText: ''
    };
  },
  mounted() {
    this.initHandle();
  },
  methods: {
    // 初始化值
    initHandle() {
      // alert('this.valueId=' + this.valueId)
      let that = this;
      // 这里要延迟执行，否则有BUG
      setTimeout(function () {
        if (that.valueId) {
          that.valueTitle = that.$refs.selectTree.getNode(that.valueId).data[
            that.props.label
          ]; // 初始化显示
          that.$refs.selectTree.setCurrentKey(that.valueId); // 设置默认选中
          that.defaultExpandedKey = [that.valueId]; // 设置默认展开
        } else {
          that.valueTitle = null; // 初始化显示
          that.$refs.selectTree&&that.$refs.selectTree.setCurrentKey(null); // 设置默认选中
        }
      }, 200);
      this.$nextTick(() => {
        let scrollWrap = document.querySelectorAll(
          '.el-scrollbar .el-select-dropdown__wrap'
        )[0];
        let scrollBar = document.querySelectorAll(
          '.el-scrollbar .el-scrollbar__bar'
        );
        scrollWrap.style.cssText =
          'margin: 0px; max-height: none; overflow: hidden;';
        scrollBar.forEach(ele => (ele.style.width = 0));
      });
    },
    // 切换选项
    handleNodeClick(node) {
      this.valueTitle = node[this.props.label || 'label'];
      this.valueId = node[this.props.value || 'id'];
      //this.$emit('getValue',this.valueId)
      this.$emit('input', this.valueId);
      this.$emit('change', this.valueId);
      this.defaultExpandedKey = [];
      this.$refs.select.handleClose()
    },
    // 清除选中
    clearHandle() {
      this.valueTitle = '';
      this.valueId = null;
      this.defaultExpandedKey = [];
      this.clearSelected();
      //this.$emit('getValue',null)
      this.$emit('input', null);
      this.$emit('change', null);
    },
    /* 清空选中样式 */
    clearSelected() {
      let allNode = document.querySelectorAll('#tree-option .el-tree-node');
      allNode.forEach(element => element.classList.remove('is-current'));
    },
    filterNode(value, data) {
      if (!value) return true;
      return data[this.props.label].indexOf(value) !== -1;
    },
    filterMethod(n) {
      this.$refs.selectTree.filter(n);
    },
    async onChange(v) {
      if (v) {
        this.$refs.selectTree.filter();
        // await this.$nextTick()
        // this.$refs.options.$el.scrollTop = 0;
      }
    }
  },
  watch: {
    value() {
      this.valueId = this.value;
      this.initHandle();
    },
    filterText(val) {
      this.$refs.selectTree.filter(val);
    }
  }
};
</script>
<style scoped>
.el-scrollbar .el-scrollbar__view .el-select-dropdown__item {
  height: auto;
  max-height: 250px;
  padding: 0;
  overflow: hidden;
  overflow-y: auto;
}
.el-select-dropdown__item.selected {
  font-weight: normal;
}
ul li >>> .el-tree .el-tree-node__content {
  height: auto;
  padding: 0 20px;
}
.el-tree-node__label {
  font-weight: normal;
}
.el-tree >>> .is-current .el-tree-node__label {
  color: #409eff;
  font-weight: 700;
}
.el-tree >>> .is-current .el-tree-node__children .el-tree-node__label {
  color: #606266;
  font-weight: normal;
}
</style>
